Evaluation of a modified multipurpose cassava processing machine for size reduction

The production of cassava (Manihot esculenta) is considered an important alternative to a reduction in food scarcity around the world. Kenya is rapidly gaining prominence due to the declining production of staple foods, especially maize and wheat. Though still considered a poor man’s food, the usage of cassava has greatly diversified in terms of both industrial and domestic applications. This coupled with the introduction of improved varieties and better farming options calls for innovative ways of handling the increasing volumes of fresh cassava tubers to minimize post-harvest losses. One of the important postharvest processes is size reduction which is achieved by either chipping or grating. Improved production methods alone are not adequate to solve the issues of field losses in cassava production. Factors affecting the efficiency of size reduction operation include operator experience, disc type, disc speed, cutting clearance and moisture content. Conventionally, this has been done manually but due to the inherent problems, the use of machines is being encouraged through the development and adoption of chipping/grating machines. In this study, the machine developed was dual-powered and allowed conversion from a chipper to a grater and vice versa as need be. It has a capacity of 162.15kg/h and 81.62 kg/h when chipping and grating respectively. The chipping process consumed less power averaging 0.0034 kW/kg compared to 0.0075 kW/kg used in the grating and these chips dried faster than manually worked cassava. Keywords: Cassava, post-harvest, chipping, grating, dual power DOI: 10.7176/ISDE/13-1-06 Publication date:June 30th 202

Evaluation of a Modified Multipurpose Cassava Processing Machine for Size Reduction

The production cassava (Manihot esculenta) is considered an important alternative to reduction in food scarcity around the world. In Kenya, it is rapidly gaining prominence due to the declining production of staple foods, especially maize and wheat. Though still considered a poor man’s food, the usage of cassava has greatly diversified in terms of both industrial and domestic applications. This coupled with the introduction of improved varieties and better farming options calls for innovative ways of handling the increasing volumes of fresh cassava tubers to minimize post-harvest losses. One of the important postharvest processes is size reduction which is achieved by either chipping or grating. Improved production methods alone are not adequate to solve the issues of field losses in cassava production. Factors affecting the efficiency of size reduction operation include operator experience, disc type, disc speed, cutting clearance and moisture content. Conventionally, this has been done manually but due to the inherent problems, use of machines is being encouraged through the development and adoption of chipping/grating machines. In this study the machine developed was dual powered and allowed conversion from a chipper to grater and vice versa as need be. It has a capacity of 162.15kg/h and 81.62 kg/h when chipping and grating respectively. The chipping process consumed less power averaging 0.0034kW/kg compared to 0.0075 kW/kg used in the grating and these chips dried faster than manually worked cassava. Keywords: Cassava, post-harvest, chipping, grating, dual power DOI: 10.7176/JBAH/13-8-03 Publication date:May 31st 202

Comparison of wall/divertor deuterium retention and plasma fueling requirements on the DIII-D, TdeV, and ASDEX-upgrade tokamaks

The authors present a comparison of the wall deuterium retention and plasma fueling requirements of three diverted tokamaks, DIII-D, TdeV, and ASDEX-Upgrade, with different fractions of graphite coverage of stainless steel or Inconel outer walls and different heating modes. Data from particle balance experiments on each tokamak demonstrate well-defined differences in wall retention of deuterium gas, even though all three tokamaks have complete graphite coverage of divertor components and all three are routinely boronized. This paper compares the evolution of the change in wall loading and net fueling efficiency for gas during dedicated experiments without Helium Glow Discharge Cleaning on the DIII-D and TdeV tokamaks. On the DIII-D tokamak, it was demonstrated that the wall loading could be increased by > 1,250 Torr-1 (equivalent to 150 {times} plasma particle content) plasma inventories resulting in an increase in fueling efficiency from 0.08 to 0.25, whereas the wall loading on the TdeV tokamak could only be increased by < 35 Torr-{ell} (equivalent to 50{times} plasma particle content) plasma inventories at a maximum fueling efficiency {approximately} 1. Data from the ASDEX-Upgrade tokamak suggests qualitative behavior of wall retention and fueling efficiency similar to DIII-D

Siting Transmission Lines in a Changed Milieu: Evolving Notions of the "Public Interest" In Balancing State and Regional Considerations

This Article discusses how state public utility law presents a barrier to the siting of new high voltage transmission lines to serve renewable resources, and how states could approach its evolution in order to preserve a role for state regulators in a new energy economy in which renewable energy will play a significant role. The traditional approach to determining the "public interest" in siting transmission lines is well on its way to obsolescence. Two developments over the past fifteen years have begun to challenge this paradigm. First, policies at the federal level and in many states have encouraged increased competition in generation, contributing to de-monopolization of the bulk power side of the industry. Second, the increased emphasis on environmental, energy independence, and other public policy objectives, has resulted in a dramatically increased demand for renewable energy, particularly given heightened attention to climate change. Given that wind power -- the most economically viable renewable resource on a bulk power basis -- is feasible predominantly in locations far removed from, load centers, the demand for new multistate transmission facilities has been brought clearly into focus. After an introduction in Part I, Part II describes the existing arrangements in several resource rich Western states for siting new transmission lines, and the coexistence of those arrangements with a conventional understanding of the public interest in determining need and addressing environmental concerns under traditional state transmission siting laws. Part III discusses transmission issues related to the competitive wholesale market and increased attention to climate change and highlights how federal law has expanded to accommodate some of these concerns. Part IV emphasizes the need for a new definition of the public interest which might better reflect these new market circumstances and opportunities, and highlights the two main barriers to this: 1) legislative and/or regulatory inertia and 2) an outdated cost-allocation model. The public interest under most state siting statutes is sufficiently capacious to give regulators some flexibility to evolve, but in other instances legislative action may be needed. In addition, the state cost-of-service ratemaking model must evolve to a more regional approach to allocating the costs of new transmission

NSTX Report on FES Joint Facilities Research Milestone 2010

Annual Target: Conduct experiments on major fusion facilities to improve understanding of the heat transport in the tokamak scrape-off layer (SOL) plasma, strengthening the basis for projecting divertor conditions in ITER. The divertor heat flux profiles and plasma characteristics in the tokamak scrape-off layer will be measured in multiple devices to investigate the underlying thermal transport processes. The unique characteristics of C-Mod, DIII-D, and NSTX will enable collection of data over a broad range of SOL and divertor parameters (e.g., collisionality ν*, beta β, parallel heat flux q||, and divertor geometry). Coordinated experiments using common analysis methods will generate a data set that will be compared with theory and simulation

Characteristics of the Scrape-Off Layer in DIII-D High-Performance Negative Central Magnetic Shear Discharges

In this paper the authors present measurements of the global power and particle balance in the high-performance phase of negative central magnetic shear (NCS) discharges and compare with reference VH-mode discharges. The principal differences observed are that NCS has a much lower fraction of the total input power flowing into the boundary, less core radiation, and larger rate of stored energy increase as a fraction of total power. Scrape-off layer (SOL) temperature and divertor heat flux profiles, and radiation profiles at the midplane, are similar to VH-mode. Due to the good core particle confinement and efficient fueling by neutral beam injection (NBI), with little gas puffing, the gas load on the walls and the recycling are very low during the NCS discharges. This results in a rate of density rise relative to beam fueling at the L to H transition time which is 1/3 of the value for VH transitions, which is in turn 1/2 that for L-to-ELMing-H-mode transitions

Investigation of Density Limit Processes in DIII-D

A series of experiments has been conducted in DIII-D to investigate density-limiting processes. The authors have studied divertor detachment and MARFEs on closed field lines and find semi-quantitative agreement with theoretical calculations of onset conditions. They have shown that the critical density for MARFE onset at low edge temperature scales as I{sub p}/a{sup 2}, i.e. similar to Greenwald scaling. They have also shown that the scaling of the critical separatrix density with heating power at partial detachment onset agrees with Borass` model. Both of these processes yield high edge density limits for reactors such as ITER. By using divertor pumping and pellet fueling they have avoided these and other processes and accessed densities > 1.5{times} Greenwald limit scaling with H-mode confinement, demonstrating that the Greenwald limit is not a fundamental limit on the core density

Investigation of physical processes limiting plasma density in H-mode on DIII-D

A series of experiments was conducted on the DIII-D tokamak to investigate the physical processes which limit density in high confinement mode (H-mode) discharges. The typical H-mode to low confinement mode (L-mode) transition limit at high density near the empirical Greenwald density limit was avoided by divertor pumping, which reduced divertor neutral pressure and prevented formation of a high density, intense radiation zone (MARFE) near the X-point. It was determined that the density decay time after pellet injection was independent of density relative to the Greenwald limit and increased non-linearly with the plasma current. Magnetohydrodynamic (MHD) activity in pellet-fueled plasmas was observed at all power levels, and often caused unacceptable confinement degradation, except when the neutral beam injected (NBI) power was {le} 3 MW. Formation of MARFEs on closed field lines was avoided with low safety factor (q) operation but was observed at high q, qualitatively consistent with theory. By using pellet fueling and optimizing discharge parameters to avoid each of these limits, an operational space was accessed in which density {approximately} 1.5 {times} Greenwald limit was achieved for 600 ms, and good H-mode confinement was maintained for 300 ms of the density flattop. More significantly, the density was successfully increased to the limit where a central radiative collapse was observed, the most fundamental density limit in tokamaks